1. Field of the Invention
The invention is directed to carbon fiber composite musical instruments.
2. Description of the Prior Art
Traditionally, instruments constructed of wood, have incorporated mechanical means, glues lamination or combinations thereof to affix separate structural pieces together. All of these methods are known to affect the tone of the instrument.
The focus in composite stringed instrument construction has been to emulate the frequency distribution of traditional wooden instruments while benefiting from the structural stability of composite materials, efficient production methods of molded construction, or both.
Composite construction has primarily utilized carbon fiber as the resin reinforcement fiber of choice, largely due to the high strength to weight ratio, the high modulus of elasticity and the low coefficient of thermal expansion. It is known that continuous carbon fibers are stronger and more durable than the bonds of glue, lamination, integrally molded dissimilar materials, a resin matrix without reinforcement of continuous fibers, and of mechanical means of affixation. Also, continuous fibers conduct energy to a higher degree than an abrupted medium, and thus both energy reflection and dissipation decrease accordingly.
A problem with achieving the ideal traditional sound of wood with a carbon fiber reinforced resin matrix is partially due to the relatively lower degree of energy absorption. The lower degree of energy absorption is desirable for sustain qualities and harmonic clarity yet it is undesirable due to the relative excess in high frequencies. This characteristic has been addressed by utilizing dampening materials such as cardboard, wood, and aramid to lower the ratio of high to low frequencies and to conduct force with respect to auditory dispersion in a manner closer to the traditionally preferred wood.
Additional factors affecting tone quality in composite construction are resin to fiber ratio, fiber orientation, resin type, resin cure temperature, preload fiber tension, fiber modulus of elasticity, area and unit density, as well as, a multitude of structural functions.
Some prior art has eliminated the use of wood due to inevitable structural variabilities and inconsistencies Thermal expansion and contraction as well as long term structural changes, such as creep and drying, also affect tone and strength. These variances when integrated with dissimilar materials can also bring rise to delamination or other structural failure.
It is common for the shape of composite acoustic guitars to replicate the traditional acoustic guitar shape. A standard shaped guitar includes an increase of the depth under the fretboard at the junction of the acoustic chamber with the heal of the neck which is approximately at the 14th fret This limits the access of the upper register, the 12th to a possible 24th fret, as it overlaps the sound chamber. The introduction of the "cutaway", a removal of the sound chamber portion adjoining the overlap, has improved access of the upper register, yet the neck design has remained unchanged The traditional increase in depth under the playing surface with a heal at the junction of the body has remained a constant. Thus, the heal and the acoustic chamber integral to the underside of the playing surface mandate a varied playing form in the transition from the lower register to the upper register.
Traditional acoustic guitar bracing provides soundboard reinforcement for string tension support. The braces are generally lengths of wood glued to the underside of the soundboard in a diverse variety of patterns. In the construct of an arch top guitar, a tailpiece is additionally implemented. Traditional violin construct, typically provides string tension support by means of a length of wood glued to the underside of the upper soundboard along the longitudinal axis relative to the bridge, a tailpiece, a bridge, and a sound post. Additional strength is inherent in the curvature and varied thickness of the soundboards. Composite acoustic construction has emulated the traditional processes.
A primary objective of the present invention is to provide a composite structure for use as a stringed instrument neck and body formed of a cast of a fiber reinforced single resin matrix including means for attaching tuning keys, a nut, a fretboard, amplification means, and a bridge.
Another objective of the present invention is to provide a composite structure for an acoustic guitar, wherein access is provided to the upper register, unobstructed by a heal or an acoustic chamber of traditional form as the acoustic chamber is not integral to the region below the playing surface.
Still, another objective of the present invention is to provide a composite guitar having a neck and body structure which includes a plurality of integral tubes and having a fiber orientation of two or more helically wound tubes integral within a helically wound tube.